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API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

Dear All,

I'm currently working on a project for a small API 650 tank (4 m3) and looking for nozzles and vessel design

I'm kind of confused about the criteria on when to consider inside projection of nozzle and shell manholes on vessel body (shell)

You can see here in this drawing that the shell manhole is projected at 72 mm

In this second image, there is no projection at all for another shell manhole.

For this Nozzel, there is a projection

Generally speaking, I found both ok, but not sure how to interpret API 650 regarding nozzle/manhole internal projection on a tank body.

Other information you may need:
  • Vertical Tank
  • This is a project with 05 similar tanks, technically the same, but they store different products (02 are flammables and the others are just corrosive)
  • Manhole is only 01 and located in the tank shell. About the nozzles, some are located on the roof and the others in the shell
  • Nozzel sizes go as minimum as 1" and maximum as 6". To be specific, 1", 2" (both SW Flanges), 3"; 4" and 6" (last three are WN Flanges) are the nozzel sizes
Can anyone share some feedback on this I'd really appreciate it


RE: API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

I believe the API-650 details show manways trimmed flush inside, and nozzles can be flush inside or extend inside as desired.
I'm not aware of any structural reason manways can't extend inside, just the longer the neck is, the more awkward it is to step through.
For roof nozzles, there is a requirement that nozzles used for venting be trimmed flush inside.

RE: API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

JStephen is correct - API 650 clearly shows manways made with reinforcing plates having necks trimmed flush and repad nozzles either flush or extending inwards from the shell. The same figure shows manway and nozzle necks with an inside projection when an insert is used. Longer manway necks are a little bit harder to get through but not that much in my opinion, especially for the 30" and 36" sizes. The neck projection inside is sometimes used for additional reinforcement of the hole in the tank shell. In a footnote, API 650 also says that you can use nozzle details in another figure for manways, so the internal projection is available if needed or wanted. Personally I would not reject a drawing or actual nozzle based on the presence or lack of an internal projection as long as proper weld details were used and there is adequate reinforcing.

RE: API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

I think they're always trimmed for personnel ergonomics, but it needs to be trimmed if you ever want to install a swiveling mixer on that manway.

RE: API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

Are you sure about the size of your tank - 4 m3?? that doesn't sound feasible to me.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: API 650 - Shell Manhole and Nozzel Inside Projection in a Vessel

If a mixer is a future option, you have to know now to make the flange and cover thicker. The internal projection may not limit a mixer swivel angle enough to matter.

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